Imaging apparatus and image correction method, and image processing apparatus and image processing method

Abstract

An imaging apparatus includes an image-capturing element, an optical axis position estimation processor, and a pixel correction unit. The optical axis position estimation processor includes a relationship calculator and an optical axis position calculator. The relationship calculator calculates a relationship between a pixel output of a phase difference detection pixel and an image height. The optical axis position calculator calculates an optical axis position of an optical system. The pixel correction unit corrects pixel outputs of the respective phase difference detection pixels in accordance with the relationship.

What is claimed is: 
     
       1. An imaging apparatus comprising:
 an image-capturing element configured such that a phase difference detection pixel for detecting a focus is provided in a part of imaging pixels; 
 an optical axis position estimation processor configured to estimate an optical axis position of an optical system configured to form an image of a subject on an image-capturing surface of the image-capturing element, from a pixel output of the phase difference detection pixel and a pixel output of the imaging pixel; and 
 a pixel correction unit configured to correct pixel outputs of the respective phase difference detection pixels, 
 wherein the optical axis position estimation processor includes: 
 a relationship calculator configured to calculate a relationship between the pixel output of the phase difference detection pixel and an image height, from the pixel output of the phase difference detection pixel and a pixel output of an image pixel near the phase difference detection pixel; and 
 an optical axis position calculator configured to calculate the optical axis position, from the relationship calculated with respect to each of a pair of the phase difference detection pixels arranged in a detection direction of a phase difference, and 
 wherein the pixel correction unit corrects pixel outputs of the respective phase difference detection pixels in accordance with the relationship. 
 
     
     
       2. The imaging apparatus of  claim 1 , wherein the pair of the phase difference detection pixels have different positions of openings, and
 the relationship calculator is configured to calculate the relationship with respect to each of the positions of the openings of the phase difference detection pixels. 
 
     
     
       3. The imaging apparatus of  claim 1 , wherein the relationship calculator is configured to calculate the relationship, from a ratio between the pixel output of the phase difference detection pixel and the pixel output of the image pixel near the phase difference detection pixel, or from a difference between the pixel output of the phase difference detection pixel and the pixel output of the image pixel near the phase difference detection pixel. 
     
     
       4. The imaging apparatus of  claim 1 , wherein the relationship calculator includes:
 a level variation detector configured to detect a variation of the pixel output of the phase difference detection pixel and the pixel output of the imaging pixel which has the same color as the phase difference detection pixel and is located in a direction different from the detection direction of the phase difference by the phase difference detection pixel; 
 a frequency variation detector configured to detect a variation of pixel outputs between a plurality of imaging pixels which are located in a direction different from the detection direction of the phase difference and have a color different from a color of the phase difference detection pixel; and 
 a picture pattern variation detector configured to detect a picture pattern variation, from a variation of pixel outputs between imaging pixels which are located near the phase difference detection pixel and the imaging pixel, the variation of the pixel outputs detected by the level variation detector. 
 
     
     
       5. The imaging apparatus of  claim 1 , wherein an influence of optical characteristics of the optical system upon the pixel outputs from the imaging pixel and the phase difference detection pixel is corrected in accordance with the optical axis position calculated by the optical axis position calculator, and
 the pixel correction unit is configured to execute correction of the pixel outputs, prior to the correction of the influence of the optical characteristics. 
 
     
     
       6. An imaging apparatus comprising:
 an image-capturing element configured such that a phase difference detection pixel for detecting a focus is provided in a part of imaging pixels; 
 an optical axis position estimation processor configured to estimate an optical axis position of an optical system configured to form an image of a subject on an image-capturing surface of the image-capturing element, from a pixel output of the phase difference detection pixel and a pixel output of the imaging pixel; and 
 a pixel correction unit configured to correct pixel outputs of the respective imaging pixels and outputs of the respective phase difference detection pixels in accordance with the relationship, 
 wherein the optical axis position estimation processor includes: 
 a relationship calculator configured to calculate a relationship between the pixel output of the phase difference detection pixel and an image height, from the pixel output of the phase difference detection pixel and a pixel output of an image pixel near the phase difference detection pixel; and 
 an optical axis position calculator configured to calculate the optical axis position, from the relationship calculated with respect to each of a pair of the phase difference detection pixels arranged in a detection direction of a phase difference, and 
 wherein the correcting unit corrects an influence of optical characteristics of the optical system upon the pixel outputs from the imaging pixel and the phase difference detection pixel, in accordance with the optical axis position calculated by the optical axis position calculator. 
 
     
     
       7. The imaging apparatus of  claim 6 , further comprising a storage unit configured to store information of the optical axis position calculated by the optical axis position calculator. 
     
     
       8. An image correction method comprising:
 calculating a relationship between a pixel output of a phase difference detection pixel of an image-capturing element and an image height, from the pixel output of the phase difference detection pixel and a pixel output of an image pixel near the phase difference detection pixel, the image-capturing element being configured such that the phase difference detection pixel, which is configured to detect a focus, is provided in a part of the imaging pixels; 
 calculating an optical axis position of an optical system, from the relationship calculated with respect to each of a pair of the phase difference detection pixels arranged in a detection direction of a phase difference; 
 storing the calculated optical axis position in a storage unit; and 
 correcting an influence of optical characteristics of the optical system upon the pixel outputs from the imaging pixel and the phase difference detection pixel, in accordance with information of the optical axis position stored in the storage unit. 
 
     
     
       9. An image processing apparatus which processes a pixel output from an image-capturing element including a phase difference detection pixel and an imaging pixel which are arranged in a detection direction of a phase difference between images obtained by dividing a pupil, the apparatus comprising:
 a first pixel output variation detector configured to detect a variation of a pixel output of the phase difference detection pixel and a pixel output of the imaging pixel which has the same color as the phase difference detection pixel and is located in a direction different from the detection direction of the phase difference by the phase difference detection pixel; 
 a second pixel output variation detector configured, to detect a variation of pixel outputs between a plurality of imaging pixels which are located near the phase difference detection pixel and the imaging pixel, which were used by the first pixel output variation detector in order to detect the variation of the pixel outputs; and 
 a pixel correction unit configured to correct pixel outputs of the respective phase difference detection pixels, from results of the first pixel output variation detector and the second pixel output variation detector. 
 
     
     
       10. An image processing method for processing a pixel output from an image-capturing element including a phase difference detection pixel and an imaging pixel which are arranged in a detection direction of a phase difference, the method comprising:
 detecting, by a first pixel output variation detector, a variation of a pixel output of the phase difference detection pixel and a pixel output of the imaging pixel which has the same color as the phase difference detection pixel and is located in a direction different from the detection direction of the phase difference by the phase difference detection pixel; 
 detecting, by a second pixel output variation detector, a variation of pixel outputs between a plurality of imaging pixels which are located near the phase difference detection pixel and the imaging pixel, which were used by the first pixel output variation detector in order to detect the variation of the pixel outputs; and 
 correcting, by a pixel correction unit, pixel outputs of the respective phase difference detection pixels, from results of the first pixel output variation detector and the second pixel output variation detector.